Abstract
The cerebellum is involved in a wide range of behaviours. A key organisational principle from animal studies is that somatotopically corresponding sensory input and motor output reside in the same cerebellar cortical areas. However, compelling evidence for a similar arrangement in humans and whether it extends to cognitive functions is lacking. To address this, we applied cerebellar optimised whole‐brain functional MRI in 20 healthy subjects. To assess spatial overlap within the sensorimotor and cognitive domains, we recorded activity to a sensory stimulus (vibrotactile) and a motor task; the Sternberg verbal working memory (VWM) task; and a verb generation paradigm. Consistent with animal data, sensory and motor activity overlapped with a somatotopic arrangement in ipsilateral areas of the anterior and posterior cerebellum. During the maintenance phase of the Sternberg task, a positive linear relationship between VWM load and activity was observed in right Lobule VI, extending into Crus I bilaterally. Articulatory movement gave rise to bilateral activity in medial Lobule VI. A conjunction of two independent language tasks localised activity during verb generation in right Lobule VI‐Crus I, which overlapped with activity during VWM. These results demonstrate spatial compartmentalisation of sensorimotor and cognitive function in the human cerebellum, with each area involved in more than one aspect of a given behaviour, consistent with an integrative function. Sensorimotor localisation was uniform across individuals, but the representation of cognitive tasks was more variable, highlighting the importance of individual scans for mapping higher order functions within the cerebellum.
Highlights
The cerebellum is critically involved in the coordination of reflex and voluntary movements, the postural base required for such movements and theReiko Ashida and Nadia L
To independently examine motor and sensory processes, we used an externally paced motor task and ‘passive’ vibrotactile stimulation targeting the upper and lower limbs; for the cognitive domain, we chose tasks that ostensibly test different domains—a verb generation paradigm and the Sternberg working memory task, though both presumably rely on verbal working memory (VWM)
Spatial normalisation/coregistration for later group analysis was performed at this stage, with boundary-based registration (Greve & Fischl, 2009) used to map each subject's functional data to their structural scan, and nonlinear registration using (FMRIB's non-linear image registration tool, part of FSL) to register structural scans to the 2 mm resolution sixth generation nonlinear Montreal Neurological Institute (MNI) brain template (Grabner et al, 2006) with 5 mm warp field control point spacing
Summary
The cerebellum is critically involved in the coordination of reflex and voluntary movements, the postural base required for such movements and the. Range of behaviours it is important to first establish whether such functions are regionally compartmentalised, and whether different facets of a given behaviour (e.g., sensory and motor components of somatic behaviour) are represented in the same spatial area It has long been known from animal studies that somatotopically organised maps are present within the cerebellum. The aims of our study, using high-resolution cerebellar optimised whole-brain fMRI in a cohort of 20 subjects, were to: (a) map within the same subjects somatic (limb and articulator) and cognitive [language and verbal working memory (VWM)] representation in the human cerebellum; (b) assess the degree of spatial overlap of different facets of somatic and cognitive function using separate sensory and motor tasks; language and VWM tasks, respectively; and (c) determine the degree of variability between subjects in these spatial maps. To independently examine motor and sensory processes, we used an externally paced motor task and ‘passive’ vibrotactile stimulation targeting the upper and lower limbs; for the cognitive domain, we chose tasks that ostensibly test different domains—a verb generation paradigm (language) and the Sternberg working memory task, though both presumably rely on VWM
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